Airpsy Mini on an RPi


#21

Do you get any error in logs (journalctl -u satnogs-client.service)?

As far as I remember, airspymini was working the last time I used it. However that was long ago.

Unfortunately a couple of parameters like the sample rate are not exposed to client, so it may be difficult to configure airspymini right.

Given that gr-satnogs is going to start using gr-soapy instead of gr-osmosdr soon, which means better support and more sdr options, I’m not sure if it would be useful to spend time to expose these missing parameters or other details in client until we perform this transition.

I’m cc’ing @surligas to give us any opinion.


#22

No errors in the logs.
Turned out to be gain. Seems the Airspy Mini is rather deaf. With the gain maxed out, I started to get some transmitters. Clearly, I would need to add an LNA into the chain where in the past it has not been needed.

Looks like I had a $114 successful failure. Hopefully I can press it into use in another project.


#23

No, please don’t! You will seriously overdrive the mini! The reason why you need to max out this specific gain setting is: the mini has three stages: LNA, MIX and IF gain! Feeding the correct setting to the correct stage is a bit of a mystery through gr-osmosdr unfortunately!

Maybe someone already found a way, but expect a rather dirty hack!


#24

Test your device with a console application first to see how the settings and signal levels compare to the other device that you are using.

This could be because the waterfall ranges need adjustment. The sample resolution in the Airspy is 12 bits vs. 8 bits in an RTL dongle. Together with decimation from a higher sample rate, this can give more than 30 dB difference in dBFS level.

You must optimize gain setting for maximum signal-to-noise ratio, not absolute power level. That’s best done using a console application unless you are very experienced with your setup.

I run two stations with Airspy R2:

OZ9AEC-VHF1 connected to a turnstile using 5 meters of coax and no pre-amp. Gain setting around 15-16

OZ7SAT connected to a Wimo X-yagi through long coax and filtered preamp. Gain setting also 15.